The present invention relates, in general, to an alarm system for the exterior of a house operable by a switch inside the house, and more particularly to an alarm unit that is connectable to an existing outside light fixture and a three-position control switch to replace the existing light switch for selectively operating the light and the alarm.
Light blinking systems used as outside alarms or visitor beacons have been known in the past. However, many of these devices are limited in their range of effectiveness to line of sight visibility so that persons indoors or otherwise hidden from the exterior light could not be alerted to an emergency situation by such devices. Furthermore, the blinking apparatus of such devices has conventionally used a relatively small bulb that could easily go unnoticed during the day.
An example of such earlier devices is U.S. Pat. No. 3,568,032 which required the installation of an additional wire between the switch and the light to produce blinking of an outside light. U.S. Pat. Nos. 4,177,408; 4,414,525; and 4,556,863 also disclose apparatus for making an outside light blink. Although no wiring changes were required for these three devices, complex electronic circuits were required in at least one of them, and all of these were expensive and difficult to install.
It is very desirable to have an outside electrical fixture such as a porch light that can instantly be switched to function as an audible/visual alarm to signal neighbors that there is an emergency situation within the house. In addition, such an alarm can be used to guide rescue crews to the correct house. This is particularly important in retirement communities or semi-rural areas where location of the correct house during an emergency is a common problem. In addition, it is desirable to have such an alarm that would be effective both day and night.